Year	Percent
1991	3.67
1992	3.89
1993	4.39
1994	4.49
1995	4
1996	2.75
1997	2.87
1998	3
1999	2.79
2000	2.13
2001	2.02
2002	1.78
2003	1.75
2004	1.74
2005	4.22
2006	2.9
2007	2.9
2008	5.51
2009	2.84
2010	2.83
2011	2.67
2012	2.27
2013	1.99
2014	2.38
2015	3.38
2016	3.41
2017	2.79